A Possible Detection of Occultation by a Proto-planetary Clump in GM Cephei

GM Cep in the young (~ 4 Myr) open cluster Trumpler 37 has been known to be an abrupt variable and to have a circumstellar disk with very active accretion. Our monitoring observations in 2009–2011 revealed the star to show sporadic ?are events, each with brightening of . 0.5 mag lasting for days. These brightening events, associated with a color change toward the blue, should originate from an increased accretion activity. Moreover, the star also underwent a brightness drop of ~ 1 mag lasting for about a month, during which the star became bluer when fainter. Such brightness drops seem to have a recurrence time scale of a year, as evidenced in our data and the photometric behavior of GM Cep over a century. Between consecutive drops, the star brightened gradually by about 1 mag and became blue at peak luminosity. We propose that the drop is caused by obscuration of the central star by an orbiting dust concentration. The UX Orionis type of activity in GM Cep therefore exemplifies the disk inhomogeneity process in transition between grain coagulation and planetesimal formation in a young circumstellar disk

Balancing conservation and economic gain: a dynamic programming approach

We optimize the trade-off between economic and ecological concerns in conservation biology by using a novel method to link a spatially explicit individual-based model to a dynamic programming model. To date, few optimality models have been presented to optimize this trade-off, especially when the common currency cannot be easily measured in dollars. We use a population simulation model (e.g. spatially explicit individual-based model) to model a hypothetical forest bird population’s response to different cutting and planting regimes. We then link these results to a dynamic programming model to determine the optimal choice a manager should make at each time step to minimize revenue foregone by not harvesting timber while maintaining a given population of birds. Our results show that if optimal management choices are made further back in time, future (terminal) reward may be greater. As the end of the management period approaches, past management practices influence the terminal reward more than future practices can. Thus if past revenue lost is high, the future reward will be low as compared to when past revenue lost is low. The general strategy of setting some minimum viable population size and then using a population simulator linked to a dynamic programming model to ask how to maintain such a population size with minimum economic loss should have nearly universal applicability in conservation biology.This research was supported by the American Ornithologists’ Union, the Maumee Valley Audubon Society, The North American Bluebird Society, The Ohio Chapter of the Nature Conservancy, The Wilson Ornithological Society and NSF grant IBN-9522064 to T.C.G

Effect of speaker age on speech recognition and perceived listening effort in older adults with hearing loss

Published online January 2012Purpose: Older adults exhibit difficulty understanding speech that has been experimentally degraded. Age-related changes to the speech mechanism lead to natural degradations in signal quality. We tested the hypothesis that older adults with hearing loss would exhibit declines in speech recognition when listening to the speech of older adults, compared with the speech of younger adults, and would report greater amounts of listening effort in this task. Methods: Nineteen individuals with age-related hearing loss completed speech recognition and listening effort scaling tasks. Both were conducted in quiet, when listening to high and low predictability phrases produced by younger and older speakers respectively. Results: No significant difference in speech recognition existed when stimuli were derived from younger or older speakers. However, perceived effort was significantly higher when listening to speech from older adults, as compared to younger adults. Conclusions: For older individuals with hearing loss, natural degradations in signal quality may require greater listening effort. However, they do not interfere with speech recognition – at least in quiet. Follow-up investigation of the effect of speaker age on speech recognition and listening effort under more challenging noise conditions appears warranted

Efeitos de diferentes níveis de desfolha nos estádios vegetativo e reprodutivo sobre desenvolvimento da cultura da soja.

JIPE 2013

Eficiência de inseticidas, quando aplicados nas sementes de soja, associados ou não com produtos aplicados na parte aérea, no controle de pragas foliares na cultura.

JIPE 2013

In search of the optimal management strategy for Arabian oryx

Extirpated from the wild in 1972 by overhunting, Arabian oryx (Oryx leucoryx) were re-introduced in Saudi Arabia in March 1990; 17 oryx were released into Mahazat as-Sayd, a 2244 km2 fenced reserve in westcentral Arabia, which lies at the periphery of their historical home range. The population has increased to 346 animals. The National Commission for Wildlife Conservation and Development, and those that manage the herd, have recently asked, ‘What is the optimal management strategy to assure long-term persistence of the species, given the absence of immigration and predation?’ Food resources, determinants of rates of mortality and birth, covary with unpredictable rainfall in Mahazat as-Sayd. Using data-driven assumptions, we developed a computer model that evaluated the probability of extinction (Pex) under various management strategies: no intervention, removing a fixed number of animals each year, removing a fixed percentage of animals each year, and removing all individuals above a threshold. In addition, we explored the probability that oryx populations would decline below two thresholds, called the probability of quasi-extinction (Pq-ex) under various management schemes. Our analyses suggested that, without intervention, the oryx population had a high Pex. Removing 15% of the current population provided a low Pex, but this method also produced high values for Pq-ex and, as a by-product, wide fluctuations in population size (N). Although it required an assessment of both N and carrying capacity (K), the most successful management plan consisted of removing all oryx above 70% of K. Adoption of this plan resulted in low Pex, low Pq-ex, and smaller fluctuations in N. Our study may provide a useful model for evaluating management plans for a variety of threatened animal populations in desert ecosystems.Funding for this project was received from the National Wildlife Research Center, Taif, Saudi Arabia, and from the Columbus Zoo, Columbus, OH

Transit Timing Analysis in the HAT-P-32 System

We present the results of 45 transit observations obtained for the transiting exoplanet HATP- 32b. The transits have been observed using several telescopes mainly throughout the YETI (Young Exoplanet Transit Initiative) network. In 25 cases, complete transit light curves with a timing precision better than 1.4 min have been obtained. These light curves have been used to refine the system properties, namely inclination i, planet-to-star radius ratio Rp/Rs, and the ratio between the semimajor axis and the stellar radius a/Rs. First analyses by Hartman et al. suggests the existence of a second planet in the system, thus we tried to find an additional body using the transit timing variation (TTV) technique. Taking also the literature data points into account, we can explain all mid-transit times by refining the linear ephemeris by 21 ms. Thus, we can exclude TTV amplitudes of more than ∼1.5min

The stellar content of the young open cluster Trumpler 37

With an apparent cluster diameter of 1.5{\deg} and an age of ~4 Myr, Trumpler 37 is an ideal target for photometric monitoring of young stars as well as for the search of planetary transits, eclipsing binaries and other sources of variability. The YETI consortium has monitored Trumpler 37 throughout 2010 and 2011 to obtain a comprehensive view of variable phenomena in this region. In this first paper we present the cluster properties and membership determination as derived from an extensive investigation of the literature. We also compared the coordinate list to some YETI images. For 1872 stars we found literature data. Among them 774 have high probability of being member and 125 a medium probability. Based on infrared data we re-calculate a cluster extinction of 0.9-1.2 mag. We can confirm the age and distance to be 3-5 Myr and ~870 pc. Stellar masses are determined from theoretical models and the mass function is fitted with a power-law index of alpha=1.90 (0.1-0.4 M_sun) and alpha=1.12 (1-10 M_sun).Comment: 9 pages, 10 figures, 2 long tables, accepte